Fuse for a projectile and applications thereof



Aug. 5, 1958 J. R. JASSE 2,845,866

FUSE FOR A PROJECTILE AND APPLICATIONS THEREOF Filed Dec. 20,1954 4 Sheets-Sheet 1 9 10 X 9 v Q I 3 14 36 11 15 gs 5 1 37 11 3o 59 16 i as 1- .1 2 2 I I 34 3a 39 r I 37 4-2 4-1 I r l 26 :23 I 23 22 2o 21 X fi ')1-v&\..+0r: 1M 1 '4? Aug. 5, 1958 "J. R. JASSE' 2,845,866

FUSE FOR A PROJECTILE AND APPLICATIONS THEREOF Filed Dec. 20, 1954 I i 4 Sheets-Sheet 2 J RV JASSE FUSE FOR A PROJECTILE AND APPLICATIONS THEREOF Filed Dec. 20, 1954 4 sheets-sheet :s

Aug. 1958 J; R. JASSE 2,845,866

FUSE FORA .PROJECTILE AND APPLICATIONS THEREOF Filed Dec. 20, 1954 4 Sheets-Sheet 4 37 16 l a a 30 y i 19 MM.- 1 )nwkw md [we gn Ha l3 7 I 2,845,8 6 V ZFUSE FORLA PROJECTILE AND APPLICATIONS THEREOF. r

Joseph Raymond Jasse, Paris, France, assignor to Societe "Nouv'elle des 'Etablissements Brandt, Paris, France, a

Fren'ch'body corporate if;"anafiti mm aa, -1954, SerialNo. 476,488 7 Claims prioritflapplication France December 24, 1953" 4lc1=lii fs, (c1; 102-18 1 The present invention relates to'self-propelled projectiles or:-ro'ckets and like machines which when launched ice the fuse in its armed condition, thati d upon impact; 1

Fig.. 4 is a side elevational'view of a movable sleeve which forms part of the arming device fortherocket;

Fig. is a longitudinal sectional viewshowingvthe j" 7 forward part of a projectile having a hollow change and.

' provided with the fuse'shown in Eigs. 1.to"4; il 2 or fired are subjected to a relatively small acceleration comprised for example' between .20 g and 150 g, g being the accelera'tion of gravity, for a certain lapse of tlme corresponding toa: travel of at least about 50 metres from 'the-launching-apparatus:

'The'inyen'tion has more particularly "the object to provide afuse suitable for incorporation in projectiles. of' the aforementioned type and which is very safe to use and extremely simple.

It has notably the object to provide a fuse of the type having a firing pin and a'detonator' support which are capable ofrelative motion, and which comprises in combination with the firing pin and the detonatorsupport: aretractablespacer device which is adapted to be interposed in its operative position between two support. surfaces,-one of which is provided on the firing .pin and the other on the detonator support, for maintaining these elements-separated from one another at rest and when. launching or firing while the acceleration of the projectilelexceeds: aminimum'safety value, which in the. ex treme case: may be zero, this 'device being automatically retracted when. the acceleration. drops belowsaid value; a lock :for maintaining the spacer device "in operative position and-an armin'g device for automatically retract ing 'saidlock when'the fuse is subjected to anacceleratio'nwhich exceeds said minimum value and has suchv duration that it couldnot occur during handling or during' an accidental; fall of the projectile provided with the fusej". I 1

1 Thus 'while I handling the projectile the arming device cannot' -bej armed and the lock remains in its operative: position" othat' it maintains the spacer device in its proper operativeposition between the'firing pin and the detonator support, thus rendering percussion impossible.- f-z 'Further',' dulr-ing the launching or firing of the projectil'ei the acceleration is -such that the arming device progressively retracts or withdraws the loc k andthereby p'er'mi'ts' th'e sp'ac'er device a to Y retract itself automatically a'ecele'ration-drops;to"said-'minirmim value (which;correspofids to safe' operation in the vicinity of the nifizzleiof thef-gunfor launching-device) and from th moment onward thefuse'is"armed.-*

' "'object'of the' inventionis to' provide' a"self-- ojctil'e or like machine and in particular "a SeH pr'Q eHed hone-w v ab e mentiondimproved fuse. p A rther featu'res "and advantages of the invention will paieiit froni'the-efisuing descliptiom i Fig. 2 is'a cross-sectional view along line -:2-2 of Fig. 6 is a partial sectional view ofa'firs t variant of the fuse of the invention showniat rest; a

Fig. 7 is a longitudinal sectional'view'of another van-- aprojectilehavingahollow charge; 7

Fig. 8 is a similar partial sectional view of a variant; of the fuse intended for.a projectilewhosestarting acceleration is low, and i Fig. 9 is a cross-sectional 7 According to the embodiments'hown in Figs.1 t'o 4,1 the fuse ofthe invention comprises Ia cylindro-ogivalf bodyl provided with a screw-threaded porti0n'2'permit-' ant of the fuse which is more particularly adaptedlfor;

' view-"aan 1 'niei 949 1035 I ting it to be screw-threadedly engaged.with..thet"end]of.= a

the projectile'withwhich it is to be combined, for'exam ple with the head B-(Fig. s of a self-propelledrocket either fgyroscopic or nonf 4 the stabilization ofwhich is gyroscopic by means of fins. 1' p A L'Ihe body 1 is provided with a throughwayaperture along its longitudinal axis XX ands'crew threadedlycn-l gaged at 6 at the forward end of this body, with respect I to the direction of flight of the projectile, is a-guide 7 I for guiding a percussion device. 'I'hisidevice'comprises a tubular member 8 which isxaxially slidable:infthe guide 7. Fitted in this manner is ahead or impact nose 9 screw-threadedly engaged with, the forward 1 screw v threaded end 10 of an axialstriker -or firing pinll the rear end of whichis in form of a ypercussiqn'point 12L The head 9 is forwardly. flared in the form "of a flange T 13 and, between the latter and the front end of theguide 7, a ring 14 of elastic material such as rubber is; disposed 'j.

around the member 8. 1 In Around the firing pin 11 is disposed a' returns 15 which bears against a rear shoulder'1'6 of the-guide 7 and furthermore against an inner flange 17 formed in the member 8. This spring 115tends to urge the'ipercus sion device into the position shown in Figijl so that a'' I flange 18 formed on the firing pin 11 encounters in the direction from the rear to the forwardend of the pro jectile, with respect to the direction of flight,the rear face of the guide member 7.

In alignment with the percussion device rear thereof, is disposed a detonator support 19 of "brass:

. or similar material which bears byarear basef20Lona thin relatively Weak washer 21 of aluminium 'or similar charge projectileprovided with the In tlie accompanying 'drawings givenimerely'by way otmaterial constituting an inner rear abutmentfinsert'edj at 22 in a ring 23. screw-threadedly engaged in the rear' tapped end ofthe body 1.

The detonator support 19 maintain a certain distance a between the point 12 of the firing pin and the primer 28. 'This spacerdevice comprises a number of balls 30 ofsteel-or similar mate- I vrial disposed in the annular space formedmjaround thei' 21,s4s,s e;+ P en A gsi s g pring l:

and at the g has a throughway aperture} I this aperture 1s smooth and cylindrical at 24 .at the'for point 12 of the firing pin between the rear conical surface 31 of the flange 18 of the firing pin and the front surface 32 of the detonator support 19. The surfaces 31 and 32' are conical and their 'apices are'rearwardly directed.

Aswill'be understood, when the fuse is subjected to an acceleration on account of its displacement with the projectile'when the latter is launched or fired, inertia tends to'apply the balls 30 on the rear seating or face 32. These balls may be expelled orurged outwardly in two possible ways, depending on whether the projectile provided with the fuse is gyroscopically stabilized (in which case the .unit rotates about the longitudinal axis of the'projecticle and the fuse) or non-gyroscopically stabilized by means of fins. These two cases will be examined in turn."

In' the case of a rotatinglself-propelledprojecticle, on account of centrifugal force, the balls 30 are urged outwardly, but the action of longitudinal acceleration combined with the presence of the conical face 32 (seating for the balls), tends to maintain theseballs in position. The apex angle of the conical face 32 is so selected that this actioncfcentrifugal force becomesp'reponderant only when the acceleration drops to a minimum value corresponding to safety of operation in the vicinity of the muzzle of the gun or launching device. This value must be so selected that, when it is attained, the projecticle has already travelled a distance for example greater than'50 metres from the muzzle, which is suflicient for ensuring that the operators of the launching deviceare safe from any premature explosion of the projecticle;

In the case of a non-rotating self-propelled projectile, theYballs '30 are capable of leaving their seating only when the acceleration 'of the projecticle has dropped to zero and the following period of deceleration has commenced at the end of thecombustion of the propelling charge. The balls are then subjected to the action of inertia which tends to project them forwardly against the front conical surface 31 which, owing to its shape, throws them outwardly.

At rest, the balls are maintained in their annular housing by a lock which forms in fact a screen around this housing. This locking screen comprises a tube 33 which is slidably mounted on the guide 7 of the percussiondevice and is disposed around the detonator support 19. It is'urgedforwardly to the position shown in Fig. 1, where it'screens off the'housing for the balls, by the action of a spring 34 which bears against the flange 20 of the detonator support 19 and against a flange 35 formed on the tube 33. The latter bears, by way of this flange 35, in the forward direction against a front flange 36 formed on a cylindrical sleeve 37.

This sleeve, which forms the main member of the arming device of the fuse, is slidable in the bore 38 of the body 1 of the fuse, this bore being itself cylindrical. It comprises on its outer face two diametrally opposed grooves 39 having a zig-zag shape. The longitudinal sides of each of these grooves comprises a series of semicircular notches, the latter being staggered from one side of the groove to the other. In each of these grooves 39 extends a locking pin or finger 40 carried by the body 1 of the fuse:(Fig. l).

Attherear, the sleeve 37 includes along its entire peripheryra notch forming a shoulder 41 which faces forwardly and is adapted to co-operate with the yieldable or resilient retaining elements formed by strips or blades formed up from a cup 43 which bears against the front face of the rear ring 23. These blades are inclined towards the axis'of the projecticle so as to hook onto the sleeve'37;when the latter, under the action of inertia, is brought into the rear position shown in Fig. 3.

,The weights of the sleeve- 37 and the tube 33 and the strengthof thespring 34 are such that the sleeve 37-- can assume the position shown in Fig. 3 (displacing the screen 33 and compressing the spring 34) only when the fuse is subjected to an acceleration of finite value and of such duration that it is impossible to obtain in the course the worst conditions of handling, for example when the projectile receives a blow or accidently falls. The inertia of these elements due to a blow at the highest velocity encountered in accidentallyfalling is insufficient to obtain a position permitting the tube 33 to unscreen the housing of the balls 30.

At rest, before firing or launching the projectile, the fuse is in the position shown in Fig. 1, the balls 30 disposed between thesurfaces 31 and 32 holding the point 12 of the firing pin away form the primer 28. These balls are held'in their housing by the locking screen 33 which is itself held in its forward position or operative position by the spring 34. The latter also holds the sleeve 37 or the arming device in its forward position. Each pin is disposed for example in the position shown in Fig. 1 and Fig. 4 at the rear of the correspondinggroove 39.

When the projectile is fired, the resultant relatively high longitudinal acceleration (30 g to g for example) causes the sleeve 37 to move rearwardly owingto its inertia, at such velocity that the grooves 39 are capable of passing by the pins 40 without jarring and without rebounding onto the latter. If the position of departure is that shown in Fig. 4, the sleeve 37 is moved in the direction of arrow f relative to the fixed pin 40 and enters into the contact with the latter at thepoint m and thereafter the sleeve continues to move rearwardly' while rotating about its own axis in the direction of arrow f 'so that theportion m n of the groove slidesover the pin 40. Then the latter reaches at 40 the apex n and the rearward-movement of the sleeve continues accompanied by a rotation in the direction opposite to that'of arrow P, the sleeve sliding over the pin 40 along the portion 0p of the opposite side of the groove.

The rearward movement of the-sleeve 37 thus continues rear seating 32 by the action of the acceleration of the projectile. When this acceleration falls to the aforementioned safety value the balls 30 are thrown outwardly, as explained above, either by the action of centrifugal force if the projectile rotates or by the action of'inertia if the projectile does not rotate andthese balls becomelodged in the forward end of the bore 38 of the body 1 of the fuse. Thenceforth the fuse is armed and nothing opposes the percussion device from approaching the dat onator support 19.

The percussion device and the detonator support are brought together when the percussion device is urged rear-- wardly relative to the projectile if the latter attains the target by its noseor head 9, this head compressing the rubber ring 14 and thus causing the firing pin 11 to move rearwardly. Furthermore, the percussion device and the detonator support are urged together in any case, even if the projectile does not attain the target by its head 9, under the action of inertia which projects the detonator support 19 forwardly so that finally the distance a! is traversed and the point 12-of thefiring pin strikes the primer 28 and thus fires the detonator which in turn ignites the explosive charge of the projectile.

' The behaviour of the projectile from the point of view of safety under various circumstances before firing or launching will now be examined.

(a) Security in the event of the proiectilefalling' If a rocket q pp with the fuse is dropped from fuse.

at 14 in respect of the first example.

spring 34, to allow theltubet 33 to ;unscreen' the annular housing-containing the balls ;30. Thefuse. therefore en counters the ground unarmed and the impact is transimittedJfro nv the: firing pin .toIthe detonaton' support 19. throughthe balls 30. But there is-no possibility of these balls becoming :bnried in the; detonator support, even if the latter is of arelatively weak material such as brass,

because the thrust communicated by the balls to the. detonator support causes, the rupture ofthe rear abutrnent constitutedfby the annularwasher 21 whichis made weak expressly forthis purpose. Thus the unit comprising ,the percussion device.and the detonator support recoil s with respect to the projectile and the point of the firing pin' is unable to strike the primer 28,-

I n the event aiblow'on the rear end of the projectile V inwhich the fuse is incorporated, the resultant suddenacceleration'of short duration jcauses the. sleeve 3 .."to

travel 'rearwar'dly to a limited extent underthe effect of inertia sothat. the side of the first notchv of each groove v391 situated above each 'pin40 (Fig. 4) suddenlyabuts againstthe latter at point Owing to the resilience .of' he material, thesleeve springs back and returns to its. initial position. .I' j

. It .willfbehoted that this does not occur under the er fectof acceleration due to, actually firing. o'r launching the projectile for. thi's'latter acceleration is of a limited. value .whichdoes n'ot res' ultfin' the sleeve 37 springing .back ,on. the pins this acceleration is, however, such] that due to the force of inertiathe' sleeve 37 is capable ofjeompressing the' spring 34. Furthermore, this a'ccel-, oration, has, .suflicient duration to ensure that the sleeve" 37f.engages-.the locks 42 in the manner described.above. Such conditions cannot'of course occur in the course'iof.

handling the fuse or the projectile equipped with this (0) Security during the first part of the trajectory 332*Thi's occuIs-onlywhenthe projectileis outside: the

' range of the operators of the launching device.

Reference will now be had to Fig. 5, which shows the fuse F of the foregoing example in position on the front part of a self-propelled rocket having a hollow charge.

This hollow charge 43 terminates at the forward end in a conical recess 44 and thus forms at 44 the usual hollow charge cavity. This cavity is of course of sufficient size to permit an unhindered rearward displacement of the detonator support 19 in the event of a blow being receive before the fuse is armed.

It will be noticed that the rear of the fuse is surrounded by a sealing sleeve 45.

The hollow charge comprises at the end of a bore 46 extending the funnel 44 a secondary detonator 47 which is adapted to be ignited by the fuse detonator F.

A variant of the fuse has been shown in Fig. 6 this variant being adapted to operate simply under the eifect of inertia, the firing pin being fixed. This firing pin 11 including its point 12 is integral with the portion 7 which is directly threadedly engaged at 6 in the body 1 of the fuse. Thus there is no rubber ring such as that shown is obtained simply under the action of inertia which The percussion charge, and. auxiliary'detonator 50 s'ervesas'a .us'enil'j 6 causes the detonator support 19 to move forwardly under the effect of the impact. The portion 7 of the firingfpinf support is preferably hollowed outat 7? so.- that tl1 is .'ele'- ment isless massive and is capable of being more easily. destroyed in thesame way as-the restof the .e w e-5 the detonatorv explodes, whereby no obstacle ism thewa of the forward-shooting explosive force produced bythe hollow charge; this is more important if the. hollowfcharge is small. n, j Q

Fig. 7 shows a variant of the fuse in posit v rocket not having a hollow charge. The front portion the ogive is seen at 48, this being filled around the 'fuse i withthe powder charge'49; v n The front part of the fuse is identical tothatj of'tl first example'and it diifers'therefrom] only 'in that the? rear support ring 23 is replaced by'a longmetnber 23? at the rear end of which is threadedly engaged'tlie auxiliary detonator 50. The element 23; constitutes an e tension which allows the free rearward movement or re coil, after rupture of the rear abutment ring. 21?, iof the unit comprising the percussion device and the idetonatonl support 19 in the' event of a blow being received before. arming; Extension 23 should be long enough to avoid that the detonator support should rebound fromthe rear of said extension, which could .bring the detonator back against the firing pin. As a result ofisaidlength, durin'g normal .percussions of the projectile, the flajnisi'fr j detonator26-Q-27 may not be sufficient tofire'thenseful and necessaryrelay to avoidjmisfiring, j Q 4 Thev fuse and its extension 23) and. the ..'auxil' natoi' 50 arehoused in a SealingQtub'eSIff i ,n

p The various above-described exaniples relate to fu s T for rockets having a relatively acceleration upon" launching or. filing, this acceleration being ap le'of' att'aining'about g as in the jcfase, forjexani e of,

fighter rockets fir'edfrom an aircraft again aircraft. 7 Figs. 8 and 9 relate to a variant of the fuse more particularly suitable for a grou ndatta intended exclusively for fighting tanks. Injth' rocket the launching acceleration is low an 7 order of 30 g, since 'the' re'qiiiredvelocity less. the maximum accelera'tionof thefuse is redu d' obvious that that arming de'vice mnsjt' opelra lower acceleration, forexample 15 g. With acceleration. for operation ofv the arming Y dling, he fuse is relatively precarious. Ho is"remedied by the following two i'rnproyenie (a) The travel of the arming 'devi c" is c increased (COm'pare'Figs V and 8 .)',fwh ich acceleration'of longer duration necessaryfor eaus'ingtne' sleeve 37 to engage under the locking blades 42.

(b) A safety pin is provided which is adapted to immobilize this sleeve 37 until required. This 'pin comprises the end 52 of a spring 53 whose shape in plan is shown in Fig. 9. This spring 53 is engaged in an outer groove 54 of the ogive 55 of the fuse and the end 52 of the spring extends radially through said ogive and enters an aperture 56 formed in the sleeve 37'".

Before launching or firing the projectile, the pin 52 is of course withdrawn. From this momentthe fuse behaves in the same way as the fuses of the preceding ex amples except that the detonator support 19* bears directly on the body 57 of the projectile on an inner unbreakable flange forming rear abutment. In this case the unit comprising the detonator support and the percussion device separated by the balls 30 is incapable of displacement, since there is no rear abutment capable of rupturing, such as the washer 21 of the preceding examples (Fig. l). The rupture of this washer is replaced in the present example, shown in Fig. 8, by a rupture of the rear part of the detonator support 19. The wall of this part is made very thin from r to s so that when a blow is received prior to arming, the thrust bustion .of the propelling charge of theprojectilel when. thislfuse'. strikes a hard obstacle such as armour plating. This maybe obtained by so selectingthehardness of at least one of the seatings for the balls 30" that beyond 1 a certain velocity of theprojectile, upon contact with the obst acle, these balls embed themselves in this seatingto such depth that the firing pin. ignites the detonator. This velocity must of course begreater than the maximum velocity developedwhen the projectile. accidentally falls so as to ensure that it, is safe. to handle. Thus. it is, necessary to select the detonatingmass insuch manner as to obtain a force of inertia which is capable of cansing the balls: to embed. themselves sufficiently in their seating. This may be, accomplished, even if a fragile rear abutment such as, the washer 21 shownv in, Fig. l or a breakable column such as, the portionrs of the detonator support 19 shown in Fig. 8 is used. The detonator support might for example bemade of brass composed of 60% copper and 40% zinc.

It will'be observed that in all the examples the detonator of the. fuse is housed inside the latter so that -its operation destroys the major part of the fuse.

without departing, from the spirit of theinvention or the scope of the appended"-claims-., I

;Having now described. my inventionwhat I claim as,

new and desire to secure-by, Letters Patent is:

1 l'. A fuse for a self-propelled projectile, subjected when.

it is. launched to. a. departure acceleration, comprising in combination; a hollow fuse body, and" disposed in.

said body: an inner rear abutment secured to said body, a detonator support bearing against saidv abutment, a detonator held on the, forward end of said detonator support; a spacer device bearing rearwardly against said detonator support and. automatically retractable when. said acceleration dropsto a minimum safety value which infthe extreme case, may be zero, whereby said fuse be.-

comes automatically armed upon the retraction of said spacer device; a firingpinv bearing rearwardly-directly against said spacer device; said spacer device, in its non-retracted position, maintaining said firing pin separated, from, said detonator, and upon retraction, re-

This. is. advantageous in the case. of a hollow charge, since no leasing said'firingepin andallowing the latter to move andjt'o travel-rearwardly towards said'det'onator held'by said"detjonatorsupport in a forwardf'po'siti'onfor fuse-J firing; said. firing pin protruding from 'tlleforwardlend of said body; one of the elements constituted by said rear abutment and said detonator'support being breakable; said detonator support moving rearwardly from its 'forward" fusefiring position rupon. breakage of said elementg in the. event of. an accidental blow on said firing pin in the unarmed conditionof said fuse, and;- sufficient to induce a rearward'travel of saidpin towards, said detonator supportand said detonator, said breakable element being ruptured by said blow, whereupon said detonator support and said detonator travel rearwardly from said forward position before said spacer device, as a result of said blow, becomes embedded in said firing pin. or insaid detonator. support to an extent sufficient" to allow the firing pin. to encounter saiddetonator; said rupture of saidbreakable element and the resultant rear ward travel of said detonator-support"and of, said detonator preventing an undesirable and untimely firing of said fuse. i

2. A fuse as claimed in claim 1, in which said. detonator support is a rigid structure and said rear abutment is breakable.

3. A fuse as claimed in claim 2, further comprising at the rear of said fuse body, a hollow extension for receiving said detonator support and said, detonator when they move rearwardly after'breakage of said rear abutment, said extension extending substantially entirely rearwardly of said rear abutment; and a second detonator attached totherear end of said extension, and relaying thefiames from the detonator held on the. forward end of said, detonator support, to the useful charge of said projectile upon normal percussions of said projectile.

4. A fuse as claimed in claim. 1, in which said rear abutment is a rigid structure, and said detonator support comprises, rearward of 'its detonator-carrying forward end, a thin walli capable of breaking when saidfiring pin receivessaid accidental. blow.

References Cited in the file of this patent UNITED STATES PATENTS 1,562,054 Remondy- Nov. 17, 1925 1,900,790 I Brandt Mar. 7', 1933' 1,944,780 Brandt Jan. 23,. 1 934 2,145,507 Denoix Jan. 31,. 1939' 2,595,757 Brandt May 6, 1952- FOREIGN; PATENTS 150,833v Australia Apr. 10,1953: 

